Gallium Nitride (GaN) is becoming increasingly more attractive for a wide range of applications, such as optoelectronics, wireless communication, automotive and power electronics. Switching GaN diodes are becoming indispensable for power electronics due to their low on-resistance and capacity to withstand high voltages. A great deal of research has been done on GaN diodes over the decades but a major issue with previous studies is the lack of explicit inclusion of electron-electron interaction, which can be quite important for high carrier densities encountered. Here we consider this electron-electron interaction, within a non-parabolic band scheme, as the first attempt at including such effects when modeling nitride devices. Electron-electron scattering is treated using a real space molecular dynamics approach, which exactly models this interaction within a semi-classical framework. Results in particular focus on the strong effect of carrier-carrier scattering on the drain side of the gate, where rapid carrier relaxation occurs.